hikey960: add a workaround for corrupted ext4 and sparse images
hikey960: add a workaround for corrupted ext4 and sparse images

For unknown reason, the ext4 image seems to be corrupted.

It looks like a regression which happened around March 14-16.
* build #49 was fine:
http://builds.96boards.org/snapshots/reference-platform/openembedded/morty/hikey960/rpb/49/
* build #51 was broken:
http://builds.96boards.org/snapshots/reference-platform/openembedded/morty/hikey960/rpb/51/

By setting explicitely IMAGE_ROOTFS_EXTRA_SPACE to 1G, we ensure the ext4 image
is big enough. Conversion to a sparse image will reduce its size as
appropriate.

Signed-off-by: Fathi Boudra <7cd6e55cc07a66bc71d7901a4cddfe6c22aab659@linaro.org>

kraj/meta-96boards,fboudra/meta-96boards,mrchapp/meta-96boards,96boards/meta-96boards,kraj/meta-96boards